Conventionally, in communicating while the driving a motor bicycle when both hands are fully occupied, or in a communication at a construction site where the hands can not be used, a headband 3C holding a bone-conduction microphone 3B is tied around the head 3A, as shown in FIG. 5. Also, as shown in FIG. 6, a helmet 4C holding a bone-conduction microphone 4B is fitted on the head 4A.
However, in both of the above techniques, the headband or the helmet must be worn on the head. This can become uncomfortable, and has created problems with respect to the appearance and the transmission of signals. Based on the above techniques, the present invention provides means which does not need to be worn on the person each time he gets on a vehicle or the like and is capable of providing communication from the operator without creating discomfort.